The invention relates to a method and apparatus for switching several electric circuits, particularly, circuit of a motor vehicle.
Such switching methods and switches are used in vehicle interiors for the control of a plurality of electric circuits and their associated electrically driven devices in the electrical system of the motor vehicle.
With conventional switching methods, switching contacts of a multi-position switch are directly electrically connected with the electric circuits to be switched.
Thus, the different illumination modesxe2x80x94parking lights, driving lights, fog lights, rear fog lights, high beams, and the likexe2x80x94are typically switched directly via a single multi-position switch.
Because of the high power drawn by certain electrically driven devices, for example the driving lights, it is necessary that the switching contacts for switching high power or high current in a traditional twelve volt wiring system be designed to inhibit wear and tear that can degrade functionality.
As a result of the necessary use of wear and tear inhibiting contacts for the switching of high power outputs, the cost of manufacturing such switches is high.
Therefore, it is an object of the present invention to provide a low cost and easily produced method and apparatus for the switching of several electric circuits of a vehicle.
In accordance with one embodiment of the present invention, control of the electric circuits of the electrical devices is not effectuated directly, but rather indirectly by means of binary codification of the positions of an actuation element by means of switching elements, e.g. micro-switches, which are not required to switch high output power.
The binary coding permits utilization of cost-effective logic modules, such as gate or processor logic, which in turn controls the electric circuits via known, low-loss, cost-effective electrical switching and or control elements such as thyristors, triacs and the like.
As a result, the use of cost-effective switches for low output power is made possible. In addition, due to the binary codification standard, cost-effective, mass-produced components can be used in the switch for a vast range of applications, inasmuch as the specific switching functions of the electric circuits are determined by the logic. Such logic may includes, for example, a gate or logic arrays, possibly programmable logic arrays, or processor logic.
These logic modules are selectively arranged at or in the switch as desired, at least during the manufacturing process, so that they can be easily exchanged.
It is, however, also contemplated that the binary codification of the switch and/or the position of its actuating element are fed via a bus system to a central logic, e.g. an on-board computer, which is also responsible for the control of additional electronic functions.
In accordance with another aspect of the present invention, the number of the coding possibilities is greater than the number of the positions of the actuating element or the desired switching modes. The redundant codification possibilities can be employed for a redundancy verification of the positions of the actuating element, or for verifying a particular switching functions.
For example, a switching element serving as a redundancy switch is additionally activated by the actuating element via a profile disk in the position of a certain mode (e.g., xe2x80x9c0xe2x80x9d or xe2x80x9c1xe2x80x9d position) to which the certain mode, which is codified, such as xe2x80x9cdriving light onxe2x80x9d has already been switched on via the other switching elements. The dual activation of a certain switching function is linked by a logical OR-gate, so that only one activation sufficesxe2x80x94i.e. either the redundancy switch or the other (codified) switchesxe2x80x94for switching on the given mode, e.g. the exemplary xe2x80x9cdriving light onxe2x80x9d mode.
It is thereby possible to ensure that a safety-related function or feature such as xe2x80x9cdriving light onxe2x80x9d operates properly despite a switch malfunction due to the redundancy. It is, of course, also possible to employ other redundancy principles as desired, rather than the described redundancy switch.
For example, it is possible to actuate the switch elements or micro-scanners via the profile disks in such a manner that each codification combination is distinguished by at least two bits from a neighboring combination (e.g., 0000, 0011, 0101, 1000, etc.) or even a randomly chosen combination. The randomly allowed combination or change is then be by a logic circuit which, in case of a dual redundancy, selectively correctively intervene and/or trigger an alarm.
Additional benefits and advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.